Choice of petrol

[Expertamateur]

I am faced with a choice. Recently purchased a s/h 2006 307cc. Engine is a 1997 (143hp) petrol. I have been driving diesels for the last 26 years so haven't been keeping up to speed with the tech. Here in France we are offered 95 and 98 which I assume has to do with the octane rating. Also I think the 98 has less of the ethanol crap added that eats rubber and plastic seals so my gut instinct is to spend the extra and go for 98. Specs for this engine say its OK to use 95. Any suggestions?

[CitroJim]

If it's anything like the UK, 95 RON petrol can have up to 10% ethanol (E10) and our 99 RON premium stuff can have up to 5% (E5) although some brands are rumoured and alleged to have none..

In your case, the car will be happy on the 95 RON fuel as all components of the fuel system should be and are likely to be compatible with ethanol and it'll have been designed to run on this grade of fuel. The only advantage of running on 98 might be that the engine can run a little more ignition advance and thus potentially run a little more economically and maybe develop a tiny smidgen more power; you ned to consider the trade-off between the likely gains and increased cost of the fuel.

For older vehicles, like my two Citroen AX with carburettors, running premium fuel is very highly recommended both from the risk of ethanol incompatibility and them being designed to run on a higher than 95 octane fuel.

[Expertamateur]

Many thanks for your insight. I was mostly thinking about the effects of ethanol, and since we do very moderate mileage now the extra cost won't be a big factor.

[CitroJim]

I was mostly thinking about the effects of ethanol, and since we do very moderate mileage now the extra cost won't be a big factor.

In that case, go for the best every time then